This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application PORTABLE COMPUTER SYSTEM CONTROLLED POWER SUPPLY OF UNIVERSAL SERIAL BUS AND METHOD OF THE SAME filed with the Korean Industrial Property Office on Jul. 23, 1998 and there duly assigned Ser. No. 29727/1998.
1. Field of the Invention
The present invention relates to a portable computer with a universal serial bus (USB) hub and a method of controlling the power supply of universal serial bus (USB) ports.
2. Background of the Invention
Recently, the demand for battery-powered portable computers has increased rapidly. However, in order to maximize the utility of such battery-powered portable computers, and thus satisfy the needs of users of such battery-powered portable computers, it is becoming increasingly necessary to maximize the time that such computers can be used before it becomes necessary to recharge the battery.
A portable computer exemplary of contemporary practice in the art incorporates a universal serial bus (USB) root hub including one or more universal serial bus (USB) ports. As is well known, universal serial bus (USB) devices are classified into self-powered devices and bus-powered devices. A self-powered universal serial bus (USB) device itself has a power source while a bus-powered universal serial bus (USB) device is supplied with power through a universal serial bus (USB) cable. The universal serial bus (USB) ports of the universal serial bus (USB) root hub are connected with bus-powered universal serial bus (USB) devices, for example, universal serial bus (USB) keyboards, universal serial bus (USB) mouses and universal serial bus (USB) monitors, and are used to connect the specific additional functions to the computer.
The universal serial bus (USB) devices implement the plug and play (PNP) function by use of the power supplied through the universal serial bus (USB) ports. If, however, the portable computer is supplied with the power from a battery, then power management of the computer is very important. Extending the use time of the battery is a significant factor for the portable computer. Since the portable computer always supplies the power to the universal serial bus (USB) ports during use of the battery, the power is unnecessarily consumed although the universal serial bus (USB) devices are not used. Specifically, for a universal serial bus (USB) device, about 100 mA current flows through each universal serial bus (USB) port in a low power state, and about 500 mA current in a high power state.
A circuit configuration of a portable computer system exemplary of contemporary practice in the art with a universal serial bus (USB) port includes a universal serial bus (USB) controller and a universal serial bus (USB) downstream port that is connected with a universal serial bus (USB) device. This portable computer exemplary of contemporary practice in the art is supplied with a direct current (DC) voltage from an alternating current (AC) adapter or a battery through a direct current (DC)/direct current (DC) converter. The universal serial bus (USB) device is suppled with power from the computer via the universal serial bus (USB) port. In the event a universal serial bus (USB)-incompatible device is connected to the universal serial bus (USB) port and so over-current flows from the direct current (DC)/direct current (DC) converter to the universal serial bus (USB) port, an over-current protection circuit blocks off the current path to the universal serial bus (USB) port. The over-current protection circuit exemplary of contemporary practice in the art can perform the foregoing function by means of a fuse or an intelligent over-current protection circuit such as a microcontroller. The intelligent over-current protection circuit detects whether the current supplied from the battery or the alternating current (AC) adapter through the direct current (DC)/direct current (DC) converter to the universal serial bus (USB) port is over-current and transmits detecting data to the universal serial bus (USB) controller. The universal serial bus (USB) controller outputs a control signal when over-current flows, so that the over-current protection circuit shuts the current path down.
In order to solve the foregoing problems, a portable computer can have a function to disable universal serial bus (USB) ports in its initializing steps by setting state of its basic input/output system (BIOS) associated with the unused universal serial bus (USB) devices. However, it can be difficult for an unskilled user to understand and suitably use the function. Furthermore, in such a case, if any universal serial bus (USB) device is connected to a universal serial bus (USB) port of the portable computer, then standby current might flow through the universal serial bus (USB) port, causing battery power consumption.
U.S. Pat. No. 3,740,569 to Carcia entitled Direct-Current Power Supply System, discloses a plurality of voltage regulator circuits connected to a battery for producing regulated positive and negative output voltages of different values. A warning circuit is provided for causing a light emitting diode to blink when the battery voltage falls below a first value. It is disclosed an automatic shutdown circuit is provided for disabling the regulator circuits when the battery voltage falls below a second and lower value. It is also disclosed an overload circuit is provided for rapidly blowing a protective fuse when the output voltage of one of the regulator circuits exceeds a desired value.
U.S. Pat. No. 4,907,183 to Tanaka entitled Battery Powered Computer System herein a Power Supply Is Selectively Shut Off When a Low Battery Power Is Detected, discloses a method and apparatus for extending the battery life in a battery powered computer system having a high power consumption peripheral device, such as a hard disk. The energy state of the power supply battery is determined by a voltage detector. When the battery voltage drops to a level below which continued ooperation of the computer system will become unreliable or impossible, battery life is extended by de-energizing any high power consumption peripheral devices such as the hard disk, thereby providing an operator with additional time to store data or secure a backup power source.
U.S. Pat. No. 4,980,836 to Carter, et al., entitled Apparatus For Reducing Computer System Power Consumption, disclose a battery powered computer system that monitors the address bus to determine when selected peripheral devices have not been accessed for a preset amount of time. When the preset amount of time has passed the system powers itself down and stops the system clock, placing it in a standby mode. It is disclosed the system is awakened by depressing a standby switch, unless there is insufficient energy in the batteries, under which circumstances an AC power source must be connected before the system can be awakened.
U.S. Pat. No. 5,163,124 to Yabe, et al. entitled Method and Apparatus For Controlling Power To Device In A Computer System, disclose a personal portable computer system that includes peripheral devices such as a printer and a CRT which can be driven by a battery power source. It is disclosed the computer system includes a computer body which contains interface units and power supplied to the interface units is controlled. The interface units are disclosed as being used for supplying power to the peripheral devices.
U.S. Pat. No. 5,237,258 to Crampton entitled Unique Computer Power System With Backup Power, discloses a computer power system that includes an AC-to-DC power supply for providing DC power to the computer during the presence of AC line power and a backup power supply for providing DC power from batteries directly to the DC operated components of the computer system, completely bypassing the AC to DC power supply, when AC line voltage is absent or low.
U.S. Pat. No. 5,767,844 to Stoye entitled Modified Universal Serial Bus Interface Implementing Remote Pomer Up While Permitting Normal Remote Power Down, discloses a remote power key function that is implemented between a remote input device having a power key and a host computer system using a four lead USB interface. Normal functioning of the USB interface and of the input device are disclosed as not affected. It is disclosed an input device includes a remote logic circuit including a transistor, a diode, and a low voltage battery. It is disclosed the remote logic circuit and MPU receive a first input from the power key and the battery and receives a second input from the host-computer provided power supply that is xe2x80x9c1xe2x80x9d if the host computer is powered-up, and xe2x80x9c0xe2x80x9d otherwise. It is disclosed a remote logic circuit output is coupled to the D+ USB interface line, and MPU output is coupled to the D+ and Dxe2x88x92 interface lines. Clamping latch logic within the host computer it is disclosed has a first input that is the D+ line, and a second input that is the power supply xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d signal. Latch logic output is input to the latch input port of the host computer power supply. It is disclosed that when the host computer is to be powered-down, the remote logic circuit first input causes the MPU to output a scan code recognized by the host computer as commanding a power-down condition.
It is therefore an object of the present invention to provide a computer with universal serial bus (USB) ports, which has a reduced power consumption and an over-current protection function.
It is another object of the present invention to provide a method of controlling the power of a portable computer with universal serial bus (USB) ports for reducing power consumption and preventing damage from an over-current.
In order to attain the above and other objects of the present invention, according to an aspect of the present invention, there is provided a portable computer system with at least one universal serial bus (USB) port, powered by an alternating current (AC) adapter or a battery, comprising a memory, a detection circuit, a control circuit, and a switching circuit. In the memory, an enabled state or a disabled state of the universal serial bus (USB) ports are stored. The detection circuit detects whether power is supplied from the alternating current (AC) adapter or the battery. The switching circuit detects whether an over-current is supplied to the universal serial bus (USB) port from the alternating current (AC) adapter or the battery. The control circuit generates a first control signal in response to a detected result from the detection circuit and the stored state of the universal serial bus (USB) port, and generates a second control signal when the over-current is detected. The switching circuit shuts down the power supplied to the universal serial bus (USB) port in response to the first control signal and the second control signal.
According to another aspect of the present invention, there is provided a method for controlling power supplied to at least one universal serial bus (USB) port of a portable computer, comprising the steps of: detecting whether an alternating current (AC) adapter is connected to the portable computer for supplying the power; reading out an enabled state or a disabled state of the universal serial bus (USB) port from a memory such as a complimentary metal oxide semiconductor (CMOS) random access memory (RAM); generating a first control signal for shutting down the power or supplying the power to the universal serial bus (USB ) port in response to the detected result and the state of the universal serial bus (USB) port; generating a second control signal when an over-current is detected from the alternating current (AC) adapter or a battery to the universal serial bus (USB) port; and switching the power supplied to the universal serial bus (USB) port in response to the first control signal and the second control signal.